The present invention relates to an air-cooled electron tube and, primarily, to an improved radiator band having abutment means for an air-cooled power tube.
Many high power electron tubes for use in UHF and VHF operation have an anode which forms a section of the envelope of the tube. In order to improve the cooling efficiency of such a tube, a plurality of discrete radiator fins are attached, for example by brazing, to the external surface of the anode. Air is passed axially through the array of radiator fins to cool the tube. A cylindrical radiator band, or collar, surrounds the radiator fins. The radiator band serves two functions. First, it contacts the outer edge of each of the radiator fins, thereby holding the inside edge of each fin against the anode during the brazing operation to secure the fins to the anode. Second, the radiator band helps to channel the flow of air through the array of radiator fins.
In order for the first function of the radiator band to be realized, each of the radiator fins must have nearly identical radial dimensions so that the radiator band will contact the outside edge of each fin and hold it against the anode during the brazing operation. It has been found that because of the variations in radial dimensions of the radiator fins, only the fins having the greatest radial dimension are contacted by the radiator band. The fins having a lesser radial dimension are not contacted by the radiator band and, thus, are not firmly attached to the anode during brazing. Improper mechanical contact of a radiator fin to the anode deleteriously effects the heat transfer from the anode and the cooling of the tube.